Process for the manufacture of viscose rayon staple



PROCESS non THE MANUFACTURE or .RAYON STAPLE Shozo Tachikawa, Higashiyama- Kyoto, Japan, by

mutual agreement of all the heirs of said Shozo Tachikawa, deceased, to Tatsuji Tachikawa, heir No Drawing. Filed Apr. 5, 1957, Ser. No. 650,818

4 Claims. (CLEO-217) This invention relatesto a process for producing rayon staple or filament having a high degree of polymerization (D.P.) from alkali cellulose. 7

Various expedients are known to the rayon art forviscosn V of the process, this second bathmay not be employed without sacrificingsome of the desirable properties of the-finished product. Because the decomposition of the xanthate radicals is controlled bythe presence of the mono amine, the regenerating bath may be satisfactorily employed; and, fifthly, the properties of the rayon staple or filament produced by the instant process are improved over thoseachievedby other processes; The properties of the spun thread are easily controlled while it is passing through the secondary bath as by properly correlating the stretching ratio to the regenerating conditions on a stepped orconical godet as shown in my Patent No. 2,732,279. 7 Both the axial properties, such as dry and wet tensile strengths, and the lateral properties, such as knot tenacity and flex life, of the'finished rayon 'ar improved as a result of the invented process.

been confinedto the spinning or coagulating and regenerative steps. in the viscose to rayon stage of the process where it is employed as an additive to the viscose for controlling the primary gel swelling of the extruded filament and for increasing the tenacity of:the rayon fibers or where it'has been used .in the production of viscose itself its/use has been restricted 'to 'the'stage previous to 'xanthation such as in the alkali cellulose steeping stage. .The mono amine is adapted to react with the zinc sulfate in the spinning bathv to'produce these desirable properties in. the final product. process of this invention mono amine exists in the spinning bath to impede the decomposition of the xant-hate radicals and to facilitate spinning in a weak acid bath, the introduction of this ammonia base salt is actually made in the previous xanthation stage. It has been found that the mono amine causes the carbon disulphide to mix easily with the surface active agent as it is soluble in each liquid. Consequently, the penetration of the carbon disulphide into the cellulose occurs at an accelerated rate ofxanthation. Due to the presence of the mono amine in the cellulose xanthate, the decomposition of the xanthate radicals is restricted and there is produced a xanthate having a [high 7 (gamma value) i.e. number of xanthate radicals per 100 glucose units of one cellulose molecule. Additionally, the xanth-ate radicals are more uniformly distributed in the viscose.

The advantages of employing the particular xanthating step of this invention are principally fivefold. Firstly, the process may employ cellulose material of very high D.P., for example 1000 to 1200 without sacrificing vis cosity, which for the viscose is usually more than 200 seconds by the ball drop test; secondly, the viscose as produced by applicants process is easily spun" in a low acid bath at a rate of to 70% higher than for conventional processes. The acid concentration of the bath may While in the V It is to be noted that no component other than'sulfuric acid is required for the spinning bath. It is unavoidable, however, that sodium sulfate will accumulate in the spinning bath; Yet in practice the sodium sulfate was found not to exceed .60 grams per'liter. Mono amines suitable for the purpose of the present invention have generally the formula R R R N, in which at least one R is an alkyl radical and the remainder H atoms. It was found that'a practical range of amines is 0.5 to 4.0% based upon the weight of the starting pulp; it is not necessary to'use more than 4.0% of the agent to produce eflfective results. g

The relation between the D.P. of the starting material and the spinning conditions is shown in Table 1 which'c'ompares theinstant process with a former process which did not employ'an amino salt in the xanthating solution. .0 a

The properties of the product prepared by the process of the present invention are shown in Table 2 in comp-arison with those of the former process.

TABLE 2 Present Process Former Process A B Denier ((1.) l. 15 1.14 1.53 Dry tenacity (g./d.) 4. 27 5. 09 3. 33 Wet tenacity (g. (1.)- 3. 08 3. 61 2. 51 Dry elon atlon percent) 12. 1 12. 9 9. 8 Flex life cycle) 600 900 300 Knot tenacity (g.ld. 2. 04 2. 45 1. 87 D.P 600 700 500 be below 20 grams per liter, which is principally due By the application of this process, the product was improved by 60% in dry tenacity, 40% in wet tenacity, 30% in dry elongation, 200% in flex life and 30% in -knot tenacity respectively, in comparison with those of the former process.

As related fully hitherto, conspicuous improvements were achieved by the present invention forthe various properties of high D.P. viscose rayon staple or filament.

Example 1 I I Wood pulp having a D.P. of 750 is steeped in 18% caustic'soda solution at 20 C. for 2 hours, squeezed to Patented July. 26, 1960-- 2.65 times the initial weight of the pulp, shredded at 15 C. to 25 C. for 2.5 hours with a mixture of carbon disulphide of 53%, triethylamine of 3.5% and Turkish red oil of 2% based on the initial weight of the pulp respectively. The cellulose xanthatethus obtained is dissolved in a diluted caustic soda solution to obtain a viscose having the viscosity of 350 see. with the cellulose concentration of 5% andtotal alkali concentration of 3%. After filtering and deaeration, the viscose is extrudedinto the spinning bath containing sulfuric acid of 12 g./l. and thereafter the gelthread is stretched step by step on a fourstepped godet (the ratio of consecutive steps is 1:2, 2:5, 5:3) immersed in the spinning bath. The thread is successively treated in a regenerating bath containing sulfuric acid of 15 grams per liter at 85 C. under stretching ratio of 15%. The final spinning velocity is 20 meters per minute.

The properties of the rayon staple or filament prepared by the process described herein are summarized on the second column of Table 2.

Example 2 25 C. for 1.5 hours and the alkali cellulose thus ob tained is successively xanthated at 18 C. to 28 C. for 2.5 hours with a mixture of carbon disulphide of 55%, triethylamine of 1% andTurkish red oil of 2% based on the initial weight of the pulp respectively. The cellulose Xanthate thus obtained is dissolved in a diluted caustic soda solution to obtain a viscose having the viscosity of 550 see. with the cellulose concentration of 5% and total alkali concentration of 3.5%. Afterfiltering and deaeration, the viscose is extruded into the spinning bath containing sulfuric acid of 4.8 grams per liter and thereafter the gel thread is stretched step by step on a five-stepped godet (the ratio of consecutive steps is 1:2, 2:5, 5:3, 3:2) immersed in the spinning bath. The'thread is successivelytreated in a regenerating bath containing sulfuric acid of 6 grams per liter at room temperature without tension.

The properties of the rayon staple or filament prepared by the process described herein are summarized in the third column of Table 2.

It is to be understood that various modifications may be made in the disclosed process without departing from the scope of invention as defined in the appended claims.

What is claimed is:

1. In the production of viscose, a process for xanthating alkali cellulose comprising the step of introducing shredded alkali cellulose into axanthating medium containing carbon disulphide, Turkey red oil as a surface active agent and a monoamine having a formula R R R N in which at least oneR is an alkyl radical and the remaining Rs are H atoms.'

2. A process for Xanthating shredded alkali cellulose as claimed in claim 1 in which the range of the monoamine in the Xanthating solution is from 0.5% to 4.0% based on the weight of the starting pulp. V

3. A process for Xanthating shredded alakil cellulose as claimed in claim 2 inwhich the monoamine is triethylamine.

4. In the production of viscose, a process for'xanthating alkali cellulose comprising the step of introducing shredded alkali cellulose into a xanthating medium containing carbon disulphide, a surface active agent and a monoamine having a formula R R R N in which at least one R is an alkyl radical and the remaining Rs are H atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,432,127 Schlosser Dec. 9, 1947 2,535,044 COX Dec. 26, 1950 2,592,355 Tachikawa Apr. 8, 1952 2,647,114 Torke July 28, 1953 2,663,704- Yehling Dec- 22, 1953 2,732,279 Tachikawa Jan. 24, 1956 2,855,321 Bachlott Oct. 7, 1958 

1. IN THE PRODUCTION OF VISCOSE, A PROCESS FOR XANTHATING ALKALI CELLULOSE COMPRISES THE STEP OF INTRODUCING SHREDDED ALKALI CELLULOSE INTO A XANTHATING MEDIUM CONTAINING CARBON DISULPHIDE, TURKEY RED OIL AS A SURFACE ACTIVE AGENT AND A MONOAMINE HAVING A FORMULA R1R2R3N IN WHICH AT LEAST ONE R IS AN ALKYL RADICAL AND THE REMAINING R''S ARE H ATOMS. 